Light emitting diode package having multiple molding resins

ABSTRACT

Disclosed is a light emitting diode (LED) package having multiple molding resins. The LED package includes a pair of lead terminals. At least portions of the pair of lead terminals are embedded in a package main body. The package main body has an opening through which the pair of lead terminals is exposed. An LED die is mounted in the opening and electrically connected to the pair of lead terminals. A first molding resin covers the LED die. A second molding resin with higher hardness than the first molding resin covers the first molding resin. Therefore, stress to be imposed on the LED die can be reduced and the deformation of the molding resins can be prevented.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/575,128, filed Oct. 15, 2007, now pending, which is hereinincorporated by reference in its entirety, and claims priority ofInternational Patent Application No. PCT/KR05/01946 filed Jun. 23, 2005,and Korean Patent Application Nos. 2004-0072452, filed Sep. 10, 2004,and 2004-0079909, filed Oct. 7, 2004 and 2005-0000269, filed Jan. 3,2005, the contents of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present invention relates to a light emitting diode package having amolding resin, and more particularly, to a light emitting diode package,in which a light emitting diode die is covered with a molding resinhaving lower hardness and then with another molding resin having higherhardness in order to alleviate stress imposed on the light emittingdiode die and to prevent the deformation of a top surface of the moldingresin.

BACKGROUND ART

In general, a light emitting diode (LED) package includes a moldingresin for covering a mounted LED die. The molding resin protects the LEDdie from the external environment. That is, the molding resin protectsthe LED die and the bonding wire from the external force and preventsthe damage of the LED die by blocking moisture from the atmosphere. Inaddition, the molding resin may contain a phosphor that can change thewavelength of light emitted from the LED die. As the result, a whitelight can be obtained using an LED die from which an ultraviolet or bluelight is emitted.

Furthermore, the LED die generates heat when emitting light. The heat istransferred to the surroundings of the LED die. Thus, the molding resincovering the LED die undergoes a thermal cycle due to the repeatedoperation of the LED die. In a case where the molding resin has higherhardness, the molding resin may be cracked or peeled during the thermalcycle. In addition, the LED die may be broken or the bonding wire may becut, due to thermal stress caused by a difference between thermalexpansion coefficients of the molding resin and the LED die. Thecracking and peeling of the molding resin lead to non-uniformity of theemitted light and deteriorates a moisture resistance characteristic.Moreover, in a case where the molding resin is formed of a thermoplasticresin, the residual stress after the curing is large, and thus, theaforementioned problem becomes worse.

An LED package capable of preventing the cracking and peeling of amolding resin due to a thermal cycle is disclosed in U.S. Pat. No.6,747,293 (Nitta, et al.) entitled “Light emitting device.” FIG. 1 is asectional view showing an LED package 500 disclosed in the above '293patent.

Referring to FIG. 1, the LED package 500 includes lead terminals 501 and502 formed out of a lead frame and a main body 503 formed integrallywith the lead terminals. The main body 503 is made of a thermoplasticresin. The lead terminals 501 and 502 are disposed in such a way thatone ends thereof face each other and the other ends thereof extend inopposite directions to project from the main body 503 to the outside.

In the meantime, the main body 503 has an opening 505 and an LED die 506is mounted on a bottom surface of the opening. The LED die 506 may beattached on one lead terminal 501 using a conductive adhesive 507 andconnected to the other lead terminal 502 through a bonding wire 509. Theopening 505 has an inclined inner wall 504 such that light emitted fromthe LED die 506 can be reflected to the outside.

A sealing resin 511 is disposed within the opening 505 in such a manneras to cover the top of the LED die 506. The sealing resin 511 is asilicone resin having a relatively high hardness of 50 to 90 in JISA ofJapanese Industrial Standards (JIS). A lens 513 is provided above thesealing resin 511 to collect light.

The sealing resin 511 of the LED package 500 has lower hardness than anepoxy resin having a hardness of 95 in JISA and thus the cracking orpeeling of the sealing resin can be prevented. In addition, since thesealing resin 511 of the LED package 500 has a relatively higherhardness as compared with a silicone resin having a hardness of 30 to 40in JISA, the external force has less influence on the LED die 506.However, since the sealing resin 511 of the LED package 500 has arelatively higher hardness as compared with the silicone resin, itcauses a relatively larger amount of residual stress when cured.Further, relatively higher thermal stress is generated due to a thermalcycle. In particular, in a case where the size of the opening or theinput power increases, the above stress increases further, therebyreducing the reliability of the LED die 506 and causing the bonding wire507 to be cut.

Meanwhile, the luminous power of an LED is substantially proportional tothe input power. Therefore, high luminous power can be obtained byincreasing the electric power input to the LED. However, the increase ofthe input power results in the increase of the junction temperature ofthe LED. The increase of the junction temperature of an LED causes theloss of photometric efficiency which represents the conversion rate ofinput energy into visible light. Therefore, it is required to preventthe junction temperature of the LED from rising due to the increasedinput power.

An example of an LED package that employs a heat sink to prevent theincrease of the LED junction temperature is disclosed in U.S. Pat. No.6,274,924B1, entitled “Surface mountable LED package.” As described inthe '924 patent, the LED die is thermally coupled on the heat sink andthus can be maintained to a lower junction temperature. Therefore, arelatively higher input power can be supplied to the LED die to obtainhigher luminous power.

In this conventional LED package, however, the heat sink can be easilyseparated from the package main body, which results in structuralinstability. When the heat sink is separated from the package main body,bonding wires that electrically connect the LED die mounted onto theheat sink with the leads are cut off to bring an irreparable damage tothe LED package. Thus, there is a need to provide an LED package inwhich the heat sink can be prevented from being separated from thepackage main body.

DISCLOSURE Technical Problem

The present invention is conceived to solve the aforementioned problemsin the art. An object of the present invention is to provide a lightemitting diode package, in which a light emitting diode die can beprotected from the surrounding environment such as external force andmoisture, stress to be imposed on the light emitting diode die can bealleviated, and the deformation of a molding resin can be preventedduring the process for sorting or assembling the LED package.

Another object of the invention is to provide a light emitting diodepackage, in which a heat sink is employed to smoothly dissipate heatgenerated from the light emitting diode die to the outside and can alsobe prevented from being separated from a package main body.

Technical Solution

According to an aspect of the present invention for solving theaforementioned technical problems, there is provided a light emittingdiode package having multiple molding resins. The light emitting diodepackage includes a pair of lead terminals. At least portions of the pairof lead terminals are embedded in a package main body. The package mainbody has an opening through which the pair of lead terminals is exposed.A light emitting diode die is mounted in the opening and electricallyconnected to the pair of lead terminals. A first molding resin coversthe light emitting diode die. Furthermore, a second molding resin withhigher hardness than the first molding resin covers the first moldingresin. Therefore, the first molding resin serves to alleviate stress tobe imposed on the light emitting diode, and the second molding resin canbe prevented from being deformed by external force.

The first molding resin may have a Durometer Shore value of less than 50A and the second molding resin may have a Durometer Shore value of noless than 50 A.

The first and second molding resins may be formed of an epoxy orsilicone resin. Further, at least one of the first and second moldingresins may contain a phosphor. In addition, the first molding resin maybe relatively thicker than the second molding resin. As a result, thestress imposed on the light emitting diode die below the first moldingresin can be further reduced.

A heat sink may be coupled to the bottom of the package main body. Theheat sink is partially exposed through the opening. The light emittingdiode die is mounted on an exposed top surface of the heat sink.Therefore, heat generated from the light emitting diode die can besmoothly dissipated to the outside through the heat sink.

The heat sink may have a base and a protrusion projecting upward from acenter portion of the base. Thus, since a heat dissipation surface canbe increased without need to increase the size of the light emittingdiode package, heat dissipation efficiency can be improved.

The heat sink may be formed with a latching step on at least one ofsides of the base and/or the protrusion. The latching step is coupled tothe package main body to prevent the heat sink from being separated fromthe package main body.

According to another aspect of the present invention, there is provideda light emitting diode package having multiple molding resins. Thepackage includes a heat sink support ring. A heat sink is fitted intothe support ring. At least two lead terminals are spaced apart from thesupport ring and heat sink, and disposed at opposite sides of thesupport ring. A package main body is molded with the heat sink and leadterminals to support the heat sink and lead terminals. The package mainbody has an opening through which the upper end of the heat sink andportions of the lead terminals are exposed. At least one light emittingdiode die is mounted on a top surface of the heat sink. Bonding wiresare used to electrically connect the light emitting diode die and thelead terminals with each other. A first molding resin covers the lightemitting diode die, and a second molding resin covers the first moldingresin. The second molding resin has higher hardness than the firstmolding resin. Thus, the first molding resin alleviates the stress to beimposed on the light emitting diode die, and the second molding resin isprevented from being deformed by external force. In addition, since theheat sink is fitted into and fixed to the support ring, the heat sinkcan be prevented from being separated from the package main body.

The first molding resin may have a Durometer Shore value of less than 50A and the second molding resin may have a Durometer Shore value of noless than 50 A.

The first and second molding resins may be formed of an epoxy orsilicone resin. Further, at least one of the first and second moldingresins may contain a phosphor.

In addition, the first molding resin may be relatively thicker than thesecond molding resin. As a result, the stress to be imposed on the lightemitting diode die below the first molding resin can be further reduced.

Meanwhile, the heat sink may have a base and a protrusion protrudingupward from the center of the base, and the protrusion is inserted intothe support ring.

The heat sink may be formed with a support ring receiving groove at aside of the protrusion. The support ring may be fastened in thereceiving groove. Thus, the heat sink can be further prevented frombeing separated from the package main body.

DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view illustrating a conventional light emittingdiode package.

FIG. 2 is a sectional view illustrating a light emitting diode packageaccording to an embodiment of the present invention.

FIG. 3 is a sectional view illustrating a light emitting diode packageaccording to another embodiment of the present invention.

FIGS. 4 to 12 illustrate a light emitting diode package employing a heatsink and a method of fabricating the same according to an embodiment ofthe present invention.

FIGS. 13 to 26 illustrate a light emitting diode package employing aheat sink and a method of fabricating the same according to anotherembodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the invention will be described indetail with reference to the accompanying drawings.

FIG. 2 is a sectional view illustrating a light emitting diode package10 according to an embodiment of the present invention.

Referring to FIG. 2, the light emitting diode (LED) package 10 includesa pair of lead terminals 11 and 13 formed out of a lead frame, and apackage main body 15. The main body 15 may be formed of a thermoplasticresin or a thermosetting resin using an insert molding process. Ingeneral, for the purpose of mass production of the LED package 10, aplurality of package main bodies 15 are formed in a lead panel where aplurality of lead frames are arranged. After molding resin (23, 25 or27) has been cured, the lead frames are cut into individual LED packages10, and the lead terminals 11 and 13 are consequently formed. The leadterminals 11 and 13 are disposed in such a manner that one ends thereofare close to face each other and the other ends thereof extend inopposite directions to protrude from the main body 15 to the outside.

At least portions of the lead terminals 11 and 13 are embedded in thepackage main body 15. That is, the main body 15 surrounds at leastportions of the lead terminals 11 and 13 to fix the lead terminalsthereto. In addition, the package main body 15 is provided with anopening 26 through which the lead terminals 11 and 13 are exposed to theoutside. An inner wall 14 of the opening 26 may be inclined such thatthe light emitted from the LED die can be reflected to the outside.

An LED die 17 is mounted on a bottom surface of the opening 26. Asillustrated in the figure, the LED die 17 may be attached on one leadterminal 11 using a conductive adhesive 19. The conductive adhesive mayinclude a silver (Ag) epoxy. Furthermore, the LED die 17 may beconnected to the other lead terminal 13 through a bonding wire 21.Accordingly, the LED die 17 is electrically connected with the leadterminals 11 and 13.

In the meantime, a first molding resin 23 covers the LED die 17. Thefirst molding resin 23 may also cover the bonding wire 21. The firstmolding resin 23 has relatively lower hardness, i.e. a Durometer Shorevalue of preferably less than 50 A, and more preferably, no more than 10A. The first molding resin 23 may be formed of an epoxy resin or asilicone resin. As illustrated in this figure, the first molding resin23 may cover the LED die 17 and the bonding wire 21, and be bonded tothe inner wall of the main body 15. Alternatively, the first moldingresin 23 may cover the LED die 17 but not extend to the inner wall ofthe package main body 15. That is, the first molding resin may belimited to a certain region in the opening.

Furthermore, a second molding resin 25 covers the first molding resin23. The second molding resin 25 is filled in the opening 26 and bondedto the inner wall 14 of the opening 26. A top surface of the secondmolding resin 25 may be flat or curved with a constant curvature.Preferably, the second molding resin 25 has relatively higher hardnessthan the first molding resin 23, i.e. a Durometer Shore value of atleast 50 A. In addition, another molding resin (not shown) may beinterposed between the first and second molding resins 23 and 25. Thesecond molding resin 25 may be formed of an epoxy resin or a siliconeresin. The second molding resin 25 and the another molding resin may beformed of the same material as the first molding resin 23. For example,in a case where the first molding resin 23 is a silicone resin, thesecond molding resin 25 is also a silicon resin. If the first and secondmolding resins 23 and 25 are made of the same material, the light lossdue to reflection on the interface between the first and second moldingresins can be reduced, and the adherence between the molding resins isincreased to improve the moisture resistance characteristic. Further,the first molding resin 23 may be thicker than the second molding resin25. Here, the thickness of the first and second molding resins 23 and 25is defined by a value measured from the top surface of the LED die 17 ina vertical direction. Since the first molding resin 23 with lowerhardness is thicker than the second molding resin 25, the stress to beimposed on the LED die 17 can be minimized. The first and second moldingresins 23 and 25 may be formed either using a mold cup or dispenser orusing a transfer molding process.

In addition, U.S. Pat. No. 6,274,924 has proposed an LED package forprotecting an LED die using a molding resin with a Durometer Shore valueof no more than 10 A. The package proposed in the '924 patent has anadvantage in that thermal stress can be alleviated by using a moldingresin having relatively lower hardness. However, the molding resin withlow hardness may be easily deformed by means of external force.

In general, after the molding resin has been formed within the LEDpackage, the lead frame is cut into individual separate packages, asdescribed above. Then, the separated packages are sorted or assembled.At this time, the molding resin with lower hardness is likely to bedeformed due to the external force. In particular, the deformation inthe top surface of the molding resin hinders uniform emission of thelight generated from the LED die.

On the other hand, in this embodiment of the present invention, thesecond molding resin 25 with relatively higher hardness covers the topof the first molding resin 23. Thus, the deformation in the top surfaceof the molding resin can be prevented. Further, since the first moldingresin 23 with relatively lower hardness is interposed between the secondmolding resin 25 and the LED diode 17, thermal stress and residualstress in the molding resin can be alleviated. This stress alleviationresults in the prevention of occurrence of cracking and peeling of themolding resins 23 and 25. Consequently, moisture penetration can beprevented, thereby improving reliability of the LED packages.

Furthermore, the first molding resin 23 and/or the second molding resin25 may contain a phosphor. The phosphor can be used to change thewavelength of light emitted from the LED die. In addition, a lens 27 maybe provided on the second molding resin 25. The lens 27 is used to allowthe light emitted from the LED die 17 to be exited at a desired viewingangle. Alternatively, the second molding resin 25 may be manufactured inthe form of a lens, for example, in a semicircular shape or Fresnel lenstype.

FIG. 3 is a sectional view illustrating an LED package 50 according toanother embodiment of the present invention.

Referring to FIG. 3, the LED package 50 includes a pair of leadterminals 51 and 53, a main body 55, an LED die 57, a conductiveadhesive 59, a first molding resin 63, and a second molding resin, asdescribed similarly with reference to FIG. 2. Similarly, the main body55 has an opening 66 of which an inner wall 54 may be inclined.

Furthermore, the LED package 50 includes a heat transfer slug or heatsink 56 connected to a lower portion of the main body 55. As illustratedin this figure, the heat sink 56 is partially exposed through theopening 66, and the LED die 57 is mounted on a top surface of theexposed heat sink 56. The heat sink may have a base and a protrusionprojecting upward from a center portion of the base. The protrusion isexposed to the outside through the opening 66. Further, the heat sink 56is configured in such a manner that the bottom surface thereof has alarger area than the exposed top surface in order to easily dissipateheat to the outside.

The LED die 57 is attached on the top surface of the heat sink 56 bymeans of the conductive adhesive 59. A bonding wire 62 connects the heatsink 56 to one lead terminal 51, and another bonding wire 61 connectsthe LED die 57 to the other lead terminal 53. As the result, the LED die57 is electrically connected to the pair of the lead terminals 51 and53.

In this embodiment, a heat sink 56 is used to easily dissipate heatgenerated from the LED die 57. Thus, the thermal stress due to a thermalcycle can be further reduced.

Hereinafter, another embodiment of an LED package employing a heat sinkwill be described in detail.

FIGS. 4 to 12 illustrate an LED package employing a heat sink and amethod of fabricating the same according to an embodiment of the presentinvention, and FIGS. 13 to 25 illustrate an LED package employing a heatsink and a method of fabricating the same according to anotherembodiment of the present invention.

FIG. 4 is a plan view illustrating an LED lead panel used for the massproduction of an LED package according to an embodiment of the presentinvention, FIG. 5 is an exploded perspective view illustrating the LEDpackage according to the embodiment of the present invention, and FIG. 6is a plan view illustrating a state where the LED package according tothe embodiment of the present invention has been formed on the LED leadpanel.

Referring to FIG. 4, an LED lead panel 101 used to fabricate an LEDpackage of the present invention includes a plurality of lead framesarranged at regular intervals. The lead frame includes lead terminals140 and connection frames 141 connecting the lead terminals to eachother. The connection frames 141 are paired to form a symmetricalstructure and formed with a hollow section 144 having a predeterminedshape at the center thereof.

In addition, the connection frame 141 is fixed to an outer frame throughthe lead terminals 140 and support leads 142. The outer frame isconfigured to surround the connection frames 141.

Although it has been described in this embodiment that the hollowsection 144 formed at the center of the symmetrical connection frame 141takes the shape of a hexagon, the present invention is not limitedthereto. The hollow section 144 may take the shape of a circle or otherpolygons with at least four vertices.

Referring to FIG. 5, after the LED lead panel 101 has been formed, apackage main body comprised of first and second housings 150 and 151 anda heat sink 153 are sequentially fixed to the LED lead panel 101.

That is, the first package housing 150 having a predetermined shape,such as a rectangular shape, is placed on the top of the pair ofconnection frames 141 which are integrally formed in the LED lead panelalong with the lead terminals 140, and the second package housing 151 isplaced on the bottom of the pair of connection frames 141.

The first package housing 150 is formed with a depressed portion at thecenter thereof in order to receive a molding resin. In a bottom of thefirst package housing 150 is formed a through-hole 158 through which theterminals and the hollow section 144 of the connection frames 141 areexposed. The through-hole 158 may have the same area as that of thedepressed portion, and an area smaller than the depressed portion asshown in the figure. The depressed portion and the through-hole 158 areformed into an opening of the package main body. On an inner wall of thedepressed portion is formed a stepped portion 159 where a molding resinof the LED package is accommodated, which will be described later.

On a top surface of the second package housing 151 is formed a receivinggroove 152 having the same shape of the connection frame 141, and on abottom surface of the second package housing 151 is formed a heat sinkseating groove 157 into which a heat sink 153 is inserted and mounted.

In addition, the second package housing 151 is formed with a circularthrough-hole 155 at the center thereof to receive a protrusion 154 ofthe heat sink 153. The top surface of the protrusion 154 may berecessed, which in turn becomes an LED seating portion 156 where an LEDchip 160 to be explained later is seated and fixed.

The first and second package housings 150 and 151 may be formed of athermal conductive plastic material or a high thermal conductive ceramicmaterial. Examples of the thermal conductive plastic material includeABS (Acrylonitrile Butadiene Styrene), LCP (Liquid Crystalline Polymer),PA (Polyamide), PPS (Polyphenylene Sulfide), TPE (ThermoplasticElastomer) and so forth. Examples of the high thermal conductive ceramicmaterial include Al2O3 (alumina), SiC (silicon carbide), AlN (aluminumnitride) and so forth. The aluminum nitride (AlN) has the sameproperties as the alumina (Al2O3) and is widely used because it issuperior to the alumina in view of thermal conductivity.

In a case where the first and second package housings 150 and 151 areformed of a thermal conductive plastic material, the housings may beplaced on the top and bottom of the symmetrical connection frames 141,respectively, and pressed at a higher temperature so that they are fixedto the LED lead panel 101. Here, the through-hole 158 and the steppedportion 159 may be formed by thermally pressing the package housing 150using a pressing means that has a protrusion corresponding to the shapeof the through-hole 158 and the stepped portion 159, after the first andsecond package housings 150 and 151 have been placed on the LED leadpanel 101. Alternatively, the first and second package housings 150 and151 may be integrally formed using an insert molding technique.

In a case where the first and second package housings 150 and 151 areformed of a ceramic material, the first and second package housings 150and 151 should be beforehand manufactured to have accurate dimensionsand shapes. Then, the first and second package housings 150 and 151formed of the ceramic material are placed above and below the connectionframes 141 of the LED lead panel 101 and then fixed to the LED leadpanel 101 using a strong adhesive or the like.

Referring to FIG. 6, the LED package is formed in the lead frame whichhas been formed on the LED lead panel 101. Therefore, a plurality of LEDpackages are formed in the LED lead panel 101.

One or more LED dice 160 are mounted into the LED seating portion 156located at the center of the heat sink 153 and electrically connected tothe connection frames 141 through bonding wires 162.

In order to electrically protect the LED die 160 mounted into the LEDseating portion 156, a Zener diode 161 may be mounted. This Zener diode161 can maintain a constant voltage and thus protect the LED die 160when static electricity or rapid high current is delivered, therebyimproving the product reliability.

FIGS. 7 and 8 are perspective views of the LED package according to thisembodiment as seen from above and below, respectively. FIG. 9 is asectional view of an LED package employing a heat sink according to thepresent invention. FIGS. 10 to 12 are sectional views illustrating amolding resin and lens formed in the LED package.

A plurality of LED packages are formed on the LED lead panel 101, andeach of the formed LED packages is cut from the LED lead panel accordingto first and second package housings 150 and 151.

Referring to FIG. 7, the lead terminals 140 are cut to a desired lengthand bent at a desired angle such that they can be mounted on a PCBsubstrate (not shown).

Further, as shown in FIG. 8, the heat sink 153 is inserted from belowthe second package housing 151 and fixed to the package main body. Atthis time, the heat sink 153 may protrude downward beyond the bottomsurface of the second package housing 151. Therefore, the surface of thedownward protruding heat sink 140 can be brought into direct contactwith the PCB substrate to thereby maximize a heat dissipation effect.

Referring to FIG. 9, in an inner space of the first package housing 150are formed two stepped portions 159 a and 159 b. These stepped portionsfunction as a fixing step when forming a molding resin or lens to beexplained later.

Furthermore, the heat sink 153 may be formed with a latching step 154 aat the side of the protrusion 154 such that the latching step 154 a canbe inserted into and fixed to a depressed portion formed in the innerwall of the through-hole 155 of the second package housing 151.Therefore, the protrusion 154 of the heat sink 153 is fixed to thethrough-hole 155 of the second package housing 151 such that the heatsink 153 is prevented from being separated from the package main body.The latching step 154 a may be formed on the base portion of the heatsink. The latching step 154 a may be formed on the uppermost edge of theprotrusion 154. At this time, the latching step 154 a is coupled to thetop surface of the second package housing 151 such that the heat sink153 can be fixed to the package main body.

Referring to FIG. 10, in the inner space of the first package housing150 is formed a first molding resin 165 which transmits light emittedfrom the LED die 160 while protecting the LED die 160 and the bondingwires 162.

The first molding resin 165 may be an epoxy resin or silicone resin andalso contain a phosphor for converting light emitted from the LED die160. Furthermore, the first molding resin 165 may contain a lightdiffuser for uniformly distributing the light.

Referring to FIG. 11, a second molding resin 167 covers the firstmolding resin 165. The second molding resin 167 is an epoxy resin orsilicone resin having higher hardness than the first molding resin 165.The second molding resin 167 may contain a phosphor and/or lightdiffuser.

The first and second molding resins 165 and 167 may be formed in theinner space of the first package housing 150, using a mold cup ordispenser or using a transfer molding technique.

Referring to FIG. 12, a lens 166 is mounted on the top of the secondmolding resin 167. The lens may be a convex lens for refracting thelight, which has emitted from the LED die 160, within a certain range ofviewing angle. The lens curvature varies according to the desiredviewing angle. The lens 166 is fixed in the stepped portion 159 b of thefirst package housing 150.

Hereinafter, another embodiment of an LED package according to thepresent invention will be described with reference to FIGS. 13 to 26.

FIG. 13 is a perspective view illustrating a lead frame 210 according toanother embodiment of the present invention.

Referring to FIG. 13, the lead frame 210 is formed with a heat sinksupport ring 213 into which a heat sink can be inserted. As shown inthis figure, the support ring 213 may take the shape of a circular ring,but the present invention is not limited thereto. The support ring 213may take the shape of a polygonal ring.

In addition, an outer frame 211 surrounds the support ring 213. Theouter frame 211 is spaced apart from the support ring 213. As shown inthis figure, the outer frame 211 may be rectangular in shape, but thepresent invention is not limited thereto. The outer frame 211 may becircular or polygonal in shape.

The support ring 213 is connected with the outer frame 211 by means ofat least two support leads 215 a and 215 b. The support leads 215 a and215 b are positioned at opposite sides of the support ring 213 andconnect the support ring 213 to the outer frame 211. In addition to thesupport leads 215 a and 215 b, additional support leads may be providedfor connecting the support ring 213 and the outer frame 211 to eachother.

Further, at least two lead terminals 217 a to 217 c and 219 a to 219 cextend from the outer frame 211 towards the support ring 213. However,these lead terminals are spaced apart from the support ring 213. Asshown in this figure, each of the lead terminals 217 a to 217 c and 219a to 219 c may be formed with a larger terminating portion at a positionnear the support ring 213. These lead terminals are preferably disposednear opposite sides of the support ring 213.

The desired number of lead terminals is determined depending on the typeand the number of diodes to be mounted and the connection mode ofbonding wires. However, it is preferred that the lead frame 210 have anumber of the lead terminals such that it can be used in various cases.As shown in this figure, since the lead terminals 217 a to 217 c and 219a to 219 c are disposed to be perpendicular to the support leads 215 aand 215 b, a number of the lead terminals can be disposed in the samedirection.

Although six lead terminals are illustrated in FIG. 13, fewer leadterminals may be disposed, or additional lead terminals may be disposed.The additional lead terminals can be disposed in the same direction asthe support leads 215 a and 215 b.

The lead frame 210 according to this embodiment of the invention can bemanufactured by pressing a plate of phosphorous bronze made of copperalloy with a die. Although only a single lead frame 210 is illustratedin FIG. 13, a plurality of lead frames 21 can be manufactured from andarranged on a single phosphorous bronze plate. In particular, for thepurpose of mass production of the LED packages, a plurality of leadframes 210 manufactured from the single phosphorous bronze plate can beused.

FIG. 14 is a flowchart illustrating a process of fabricating an LEDpackage according to an embodiment of the present invention. FIGS. 15 to26 are perspective and plan views illustrating the method of fabricatingthe LED packages in accordance with the process of FIG. 14.

Referring to FIG. 14, the lead frame 210 of FIG. 13 is first prepared(S01). As described above, the lead frame 210 can be manufactured bypressing the phosphorous bronze plate. In addition, the plurality oflead frames can be formed from and arranged on a single phosphorousbronze plate.

Referring to FIGS. 14 and 15, a heat sink 220 which can be inserted andfixed to the support ring 213 of the lead frame 210 is prepared. Theheat sink 220 has a top surface on which an LED die can be mounted.Preferably, the size of the top surface of the heat sink 220 is smallerthan the inner diameter of the support ring 213 such that the heat sink220 can be easily inserted into the support ring 213, and the side ofthe heat sink 220 has an outer diameter larger than the inner diameterof the support ring 213.

Further, the heat sink 220 can be formed with a support ring receivinggroove 223 a in which the support ring 213 is inserted and coupled.Furthermore, the receiving groove 223 a can be provided in a spiral formsuch that the support ring 213 can be easily fastened to the groove 223a.

The heat sink 220 may have a base 221 and a protrusion 223 thatprotrudes upward from a center portion of the base 221. Here, thereceiving groove 223 a is formed on the side of the protrusion 223. Asshown in the figures, the base 221 and the protrusion 223 can becylindrical, but the present invention is not limited thereto. The baseand protrusion may take the shape of a polygonal casing. The protrusion223 can be shaped similar to an inner shape of the support ring 213, butthe present invention is not limited thereto. That is, the support ring213 may take the shape of a circular ring whereas the protrusion 223 maytake the shape of a rectangular casing.

The heat sink 220 can be formed of a metal with high thermalconductivity or a thermal conductive resin using a pressing or moldingtechnique. In addition, the heat sink 220 is fabricated separately fromthe lead frame 210. Thus, step S01 of preparing the lead frame 210 andstep S03 of preparing the heat sink 220 can be changed in order orperformed at the same time.

Referring to FIGS. 14 and 16, the heat sink 220 is inserted into andfixed to the support ring 213 of the lead frame 210 (S05). Since theouter diameter of the side of the heat sink 220 is larger than the innerdiameter of the support ring 213, the heat sink 220 may be forciblyinserted into and fixed to the support ring 213.

On the other hand, in a case where the support ring receiving groove 223a is formed, the support ring 213 is accepted into the receiving 223 ato support the heat sink 220. At this time, a part of the support ring213 is received in the receiving groove 223 a and the remaining partthereof preferably protrudes outward from the protrusion 223. Inaddition, in a case where the receiving groove 223 a is spiral, the heatsink 220 can be inserted into the support ring 213 by rotating the heatsink 220.

Referring to FIGS. 14 and 17, after the heat sink 220 has been fixed tothe lead frame 210, a package main body 230 is formed using an insertmolding technique (S07). The package main body 230 can be formed of athermosetting or thermoplastic resin using an injection molding process.

The package main body 230 is formed around the heat sink 220 to supportthe support ring 213, the support leads 215 a and 215 b, the leadterminals 217 a to 217 c and 219 a to 219 c, and the heat sink 220. Thesupport leads and the lead terminals partially protrude outward from thepackage main body. In addition, the package main body 230 has an openingthrough which an upper end of the heat sink 210 and the lead terminalsare exposed.

As shown in FIG. 17, portions of the support leads 215 a and 215 b andthe support ring 213 can be exposed through the opening. Accordingly, agroove or recess is formed in the package main body 230 a.Alternatively, as shown in FIG. 18, the package main body 230 a maycover most portions of the heat sink 220, the support ring, the supportleads and the lead terminals except for the upper end of the heat sink,and portions of the lead terminals. To this end, several openings may beprovided. Even in this case, a groove or recess surrounded by a sidewall of the main body 230 a may be also formed on the upper portion ofthe package main body 230 a, as shown in the figure. In addition, thebottom surface of the heat sink 220 is exposed to the outside.Furthermore, the side surface of the base 221 can be exposed to theoutside. In this way, the heat dissipation through the heat sink 220 canbe promoted.

As shown in FIGS. 17 and 18, the package main body 230 or 230 a can beshaped as a cylinder, but the present invention is not limited thereto.The main body may be shaped as a polygonal casing such as a rectangularcasing.

Since the heat sink 220 is coupled to the lead frame 210 and the packagemain body 230 is then formed of a thermosetting or thermoplastic resinusing an injection molding process, the heat sink 220 can be stronglycoupled to the package main body 230.

Referring to FIGS. 14 and 19, the support leads 215 a and 215 bprotruding outward from the package main body 230 are cut and removed(S09). As a result, the cut support leads 216 a and 216 b remain in thepackage main body 230, and thus, the remaining support leads and thesupport ring 213 can further prevent the heat sink 220 from beingseparated from the package main body 230.

In the meantime, when cutting out the support leads, the lead terminalsprotruding outward from the package main body 230 can also be cut andremoved, except lead terminals used for the supply of electric current.For example, as shown in FIG. 20, if only two lead terminals 217 c and219 c are required, the other lead terminals 217 a, 217 b, 219 a and 219b will be cut and removed. In addition, as shown in FIG. 21, if fourlead terminals 217 a, 217 c, 219 a and 219 c are required, the otherlead terminals 217 b and 219 b will be cut and removed.

The aforementioned step of cutting and removing the lead terminals isperformed only when the lead terminals prepared in the lead frame 210are more than required in an LED package. Thus, when the number of leadterminals required in the LED package is the same as the number of leadterminals prepared in the lead frame 210, the above step of cutting andremoving the lead terminals needs not be performed. In addition, eventhough extra lead terminals remain, they do not have influence on theoperation of the LED package. Therefore, it is not necessarily to cutand remove the extra lead terminals.

Referring to FIGS. 14 and 22, an LED die 240 is mounted on the topsurface of the heat sink 220. The LED die 240 may be a so-calledone-bond die having electrodes on the upper and lower surfaces thereofor a so-called two-bond die having two electrodes on the upper surfacethereof.

In a case where the LED die 240 is a one-bond die, the heat sink ispreferably formed of an electrical conductive metal. In this case, theLED die 240 is mounted on the heat sink 220 using an electricalconductive adhesive such as a silver epoxy. Alternatively, in a casewhere all the LED dice mounted on the heat sink 220 are two-bond dice,the heat sink 220 needs not be electrically conductive. Further, the LEDdice can be mounted on the heat sink 220 using a variety of thermalconductive adhesives in addition to a silver epoxy.

Meanwhile, a plurality of LED dice 240 can be mounted on the heat sink220. In addition, the plurality of LED dice 240 can include a variety ofLED dice that emit light of different wavelengths. For example, as shownin FIG. 22, three LED dice 240 can be mounted on the heat sink. At thistime, the three LED dice 240 can emit red, green and blue lights,respectively. Thus, the LED package can realize light of all colors byemploying the three LED dice 240.

Referring to FIGS. 14 and 23, the LED dice 241, 243 and 245 areelectrically connected to the lead terminals 217 a to 217 c and 219 a to219 c, respectively, through the bonding wires (S13). In a case wherethe LED dice 241, 243 and 245 are all two-bond dice, each of the LEDdice is connected to the two corresponding lead terminals through thetwo corresponding bonding wires. That is, as shown in the figure, therespective LED dice 241, 243 and 245 can be electrically connected todifferent pairs of the lead terminals, respectively. Alternatively, therespective LED dice are connected to one common lead terminal (forexample, 217 b) through the bonding wires, and also connected to thedifferent lead terminals (for example, 219 a, 219 b and 219 c) that areplaced in opposition to the common lead terminal. In this case, the LEDdice can be driven by means of different electric currents.

On the other hand, as shown in FIG. 24, a one-bond die 241 a andtwo-bond dice 243 and 245 can be mounted together. At this time, one ofthe lead terminals 217 b is electrically connected to the heat sink 220through a bonding wire. Thus, the lead terminal 217 b is electricallyconnected to a bottom surface of the one-bond die 241 a through thebonding wire and the heat sink 220. Since a variety of combinations ofone-bond dice and two-bond dice can be made, the bonding wire connectionfor each combination can also be performed in various modes.

In addition, the lead terminals and the LED dice can be connected toeach other in various ways, and a plurality of LED dice can be connectedto each other in parallel, series or series-parallel configurations.

After the LED dice 241, 243 and 245 and the lead terminals are connectedthrough the bonding wires, the LED dice 241, 243 and 245 are sealedusing first and second molding resins (not shown) (S15). The moldingresins are filled in the opening of the package main body 230 to therebyseal the LED dice and the bonding wires.

In addition, the first and/or second molding resin can incorporate aphosphor. For example, the phosphor can be a phosphor that converts bluelight into yellow, or green and red light. Thus, in a case where an LEDdie for emitting blue light is mounted on the heat sink 220, a portionof the light emitted from the LED die can be converted into yellow, orgreen and red light, so that an LED package for emitting white light tothe outside can be provided. Furthermore, the molding resins mayincorporate a diffuser. The diffuser distributes the light emitted fromthe LED dice such that the LED dice and the bonding wires can beprevented from being viewed from the outside and the light can beuniformly radiated to the outside.

After the LED dice are sealed by the molding resins, a lens 250 isformed on the top of the package main body 230 (S17) as shown in FIG.26. The lens is used to emit light within a certain viewing angle andmay be omitted if a lens needs not be employed. In particular, thesecond molding resin may be cured in the form of a lens to function as alens. At this time, the step of forming a lens can be omitted.

Referring to FIGS. 14 and 25, the lead terminals 217 a to 217 c and 219a to 219 c are cut and bent from the outer frame 211 (S19). Finally, asurface mountable LED package is completed. Meanwhile, step S09 ofcutting and removing the support leads may be performed together in stepS19.

Hereinafter, the LED package according to this embodiment will bedescribed in detail with reference to FIG. 25.

Referring again to FIG. 25, the LED package includes the heat sinksupport ring 213. The support ring 213 is formed of a copper alloy suchas phosphorous bronze. As shown in the figure, the support ring 213 canbe shaped as a circular ring, but the present invention is not limitedthereto. The support ring may be shaped as a polygonal ring. The cutsupport leads 216 a and 216 b are extended outward from the support ring213. The cut support leads 216 a and 216 b may be disposed at oppositesides of the support ring 213.

The heat sink 220, which was described in connection with FIG. 15, isinserted into the support ring 213. Meanwhile, at least two leadterminals 217 a to 217 c and 219 a to 219 c are disposed at both sidesof the support ring and are spaced apart from the support ring 213 andthe heat sink 220. The lead terminals may be bent to be surface-mounted.

Furthermore, the package main body 230 is molded to support the heatsink 220 and the lead terminals. The package main body 230 has anopening at the upper portion thereof, through which the upper end of theheat sink 220 and parts of the lead terminals are exposed. Meanwhile,the lead terminals penetrate through the side wall of the package mainbody 230 and protrude outward from the side wall of the main body.

As explained with reference to FIG. 17, portions of the support leads215 a and 215 b and the support ring 213 may be exposed through theopening. Thus, a groove or recess is formed in the package main body230. In addition, as explained with reference to FIG. 18, the packagemain body 230 a may cover most of the heat sink, the support ring, thesupport leads and the lead terminals except for the upper end of theheat sink and portions of the lead terminals. Thus, several openings maybe formed. Even in this case, the package main body 230 a is preferablyformed with a groove or recess surrounded by the side wall of thepackage main body, as shown in FIG. 18. The package main body 230 may bea plastic resin formed by an injection molding of a thermoplastic resinafter the heat sink 220 is inserted into and fixed to the support ring213.

In addition, the LED dice 241, 243 and 245 are mounted on the topsurface of the heat sink 220. Although the LED dice shown in FIG. 25 areillustrated as the two-bond dice, but the present invention is notlimited thereto. For example, the LED dice may be either one-bond diceor the combination of one-bond dice and two-bond dice.

The LED dice are electrically connected to the lead terminals throughbonding wires. In a case where the LED dice are two-bond dice, each ofthe LED dice is electrically connected to two lead terminals through twobonding wires. Alternatively, in a case where at least one of the LEDdice is a one-bond die, the heat sink is electrically connected to atleast one of the lead terminals through the bonding wire.

The LED dice may be connected with the lead terminals in various waysaccording to the required characteristics of the LED package.

In the meantime, the first and second sealing resins (not shown) coverand seal the LED dice. The grooves formed on the upper portion of thepackage main body 230 are filled with the sealing resins. In addition,the sealing resins may contain a phosphor and/or a diffuser. As shown inFIG. 26, the lens 250 may be further formed in the package main body230. Alternatively, the second sealing resin may be formed in the shapeof a lens to thereby function as a lens.

According to the present invention, there is provided an LED package, inwhich LED dice can be protected from surrounding environments such asexternal force and moisture, the stress to be imposed on the LED dicecan be alleviated, and the deformation of the molding resin can beprevented during the sorting and assembly. Further, the presentinvention can provide an LED package, in which a heat sink is employedto smoothly dissipate heat generated from the LED dice, and the heatsink cannot be separated from the package main body.

1. A light emitting diode package having multiple molding resins,comprising: a heat sink support ring; a heat sink inserted into thesupport ring; at least two lead terminals disposed at both sides of thesupport ring and spaced apart from the support ring and heat sink; apackage main body molded with the heat sink and lead terminals tosupport the heat sink and lead terminals, the package main body havingan opening through which the upper end of the heat sink and portions ofthe lead terminals are exposed; at least a light emitting diode diemounted on a top surface of the heat sink; bonding wires forelectrically connecting the light emitting diode die and lead terminals;a first molding resin covering the light emitting diode die; and asecond molding resin covering the first molding resin and having higherhardness than the first molding resin.
 2. The light emitting diodepackage as claimed in claim 1, wherein the first molding resin has aDurometer Shore value of less than 50 A and the second molding resin hasa Durometer Shore value of no less than 50 A.
 3. The light emittingdiode package as claimed in claim 2, wherein the first and secondmolding resins are formed of an epoxy or silicone resin.
 4. The lightemitting diode package as claimed in claim 3, wherein the second moldingresin is formed in the shape of a lens.
 5. The light emitting diodepackage as claimed in claim 1, wherein the heat sink has a base and aprotrusion projecting upward from the center portion of the base andinserted into the support ring.
 6. The light emitting diode package asclaimed in claim 5, wherein the heat sink is further formed with asupport ring receiving groove at a side of the protrusion to receive thesupport ring.
 7. The light emitting diode package as claimed in claim 1,wherein the package main body is formed of a thermosetting resin or athermoplastic resin by insert molding the lead terminals and heat sink.